It depends. They can do such things as split, combine, give something off, or be converted into energy, to name a few.
atoms
In a chain reaction, neutrons released during the splitting of an initial nucleus trigger a series of nuclear fissions.
hydrogen
Hydrogen nuclei, which are protons
gfytu
subatonic particles
j.j. Thompson
Radiation
atoms
In a chain reaction, neutrons released during the splitting of an initial nucleus trigger a series of nuclear fissions.
Can be alpha, beta particles in radioactive decay, or neutrons in fission. There is also gamma ray energy which is part of the EM spectrum I believe the answer your looking for is Radiation
Particles in an atom have opposite electrical charges, which cause the particles to attract each other, kind of like how positive and negative magnets stick together.
hydrogen
a meltdown
helium-4
Hydrogen nuclei, which are protons
The chemical reaction goes faster if calcium carbonate is powdered.